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The Wonder Gene

Bodybuilders would strangle to get their hands on it: a wonder gene of sorts that has been found to increase muscle mass without having to pump so much as a pound of iron.

There’s just one catch: Nature has bestowed the mysterious genetic trait, which is caused by a rare mutation, on sheep only. There’s no human version.

Whether the sheep industry can take advantage of what has turned out to be a Jekyll and Hyde development is going to depend a lot on research. Helping look into the matter are Oregon State University’s Department of Animal Sciences and Department of Nutrition and Food Management.

A ewe and twin lambs, which don't carry the muscle-growing Callipyge gene, at Oregon State University's Sheep Center west of campus. Photo: Howard Meyer

Howard Meyer, a professor of animal science at OSU and one of the country’s experts on sheep, said that the mutant gene was first discovered in the mid-1980s by a breeder in Oklahoma. The breeder’s find went more or less unnoticed until he began entering the gene-carriers in big-money lamb judging contests, and they ended up bleating all the way to the bank. As it turned out, the gene, which is defined as a “spontaneous mutation,” was traced back to one of the breeder’s rams, who is believed to be the first in the world to carry it. The animal’s name? Solid Gold, appropriately.

So, can the gene help revive a sagging U.S. lamb industry? Right now it’s anybody’s guess.

Lamb has never been a big hit with American meat eaters. One of the reasons, said Meyer, can be traced back to World War II and the South Pacific. At that time, a big part of a soldier’s diet consisted of cheaper cuts of old, tough, rather pungent Australian mutton. (Mutton is meat from sheep over one year old; lamb is the meat of younger animals.)

To compound the matter, the soldier’s meals were being “prepared” by military cooks, who, it can be safely said, probably knew more about field stripping an M-1 rifle than they did about tenderizing a leg of sheep.

Making the matter even worse, said Meyer, is that many of these dishes were served aboard rocking and rolling ships full of seasick men about to assault a beachhead. Is it any wonder that when the war was over, the first thing a serviceman asked for when he got back home was not a lamb chop?

Today, the per capita intake of lamb (very little mutton is consumed in this country) in the United States is less than one pound per person, compared to a little over 60 pounds of beef. Meyer explained, “That doesn’t mean each person in the country only eats a little bit (of lamb). It means that the lamb consumers eat quite a lot and the vast majority don’t eat it at all.”

Both lambs are about six months old. The burly one on the left has the Callipyge gene. Also in the photograph are OSU graduate students Dan Williams, left, and Harri Baskar Srinvasan. Photo: Bob Rost

Most of the big consumers, he said, are found on the East and West Coasts, where the population tends to be more cosmopolitan and made up of people who trace their origins back to sheep-eating countries such as England, France, Greece and Spain.

It’s interesting to note that it was one of Meyer’s former doctoral students at OSU who “mapped” the muscle-growing gene (pinpointed its location on the chromosome) and named it. The name is a mouthful: Callipyge (pronounced cal-LIP-pidgee).

People who say scientists don’t have a sense of humor will take that back when they hear what the name stands for. Callipyge is Greek for “beautifully proportioned tush,” the fabulous fannies found on the gene-carrying sheep being an obvious tipoff to the gene’s presence.

So why isn’t America welcoming the Callipyge-carrying sheep with open mouths? Isn’t leaner meat what we’re all clamoring for? Don’t sheep farmers want to get more for their animals? Don’t packers want higher carcass weights?

The answers are yes, yes and yes. However, above all else, consumers demand that their loin chops be tender, and the mucho muscle-making Callipyge gene has the disadvantage of, horror of horrors, producing tougher muscle as well.

Meyer explained that lamb chops, which are the most popular and pricey part of the animal, are traditionally lots more tender than beef, so tender you can cut them with a fork. Lambs carrying the muscle gene, however, produce meat that equals beef in texture. “For a beef consumer, the meat would be judged okay; for a lamb consumer, the meat would be judged too tough,” he said. The result is that several lamb packers have refused to handle the heavier-muscled lambs until the toughness issue is resolved.

In 1992 OSU became one of the half-dozen universities in the country to get involved with Callipyge research. That year, with the aid of some funds provided by a West Coast lamb packer, Meyer acquired six Dorset gene-carrying rams from a United States Department of Agriculture research center in Nebraska. He then began mating the animals with ewes of different breeds owned by OSU, with the intent of evaluating the meat produced by the unions.

Meyer explained that the way the gene works, about half of the lambs from the matings contain the gene and show, or “express,” the heavier-muscled characteristics being studied.

Another phase of the research program is taking place in OSU’s Nutrition and Food Management kitchen. There, answers to the toughness problem could be cooked up, so to speak.

In the test kitchen muscles from various cuts of lamb—the loin, shoulder, leg, etc.—are cooked using various methods—roasting, broiling, grilling—in an attempt to see if preparation is the solution to reducing meat toughness. Conducting the cooking experiments is Haribaskar Srinivasan, one of Meyer’s students, who is studying for his master’s degree.

Meyer said that when grilled, lamb loin chops are very tough. However, cooking studies have revealed that when individual leg muscles of lamb are roasted, there is no difference between heavy-muscled and normal animals. “It may be that this heavy muscle gene makes some muscle tough and may not have any effect on others,” noted Meyer.

OSU also is conducting physiology studies on Callipyge-carrying sheep, said Meyer. “We’re trying to find out what makes them different, what brings about this dramatic change. What’s going on in these animals?” He’s not sure whether or not such findings “will be particularly revealing” for the gene-carrying sheep, but he’s hoping they will help in selecting normal sheep for muscularity traits. The key may be in hormones or enzymes that are being studied as animals grow.

Meyer said that through the years breeders have tried, with limited success, to increase muscle mass in sheep through traditional breeding methods. One of the problems is that, until the discovery of the Callipyge gene, it was practically impossible to tell how heavily-muscled a sheep was until it was slaughtered.

“We try to assess muscling in animals by judging them, feeling their muscularity, but even judges find it hard to know if they’re feeling muscle or fat,” he said.

Illustration: Tom Weeks

Such is not the case with the new “breed” of lamb carrying the Callipyge gene. The muscles are easy to feel because “they’re packed in there really tight,” giving a feel similar to that of cramped muscles, said Meyer. “The sheep (with the gene) even walk differently; they walk somewhat like a bodybuilder, almost a bit of a swagger.”

Meyer said that a normal lamb will usually dress out at about 52 percent carcass weight, the carcass defined by Meyer as “what you see hanging in the cooler.” Sheep with the Callipyge gene, however, dress out at 56 percent. At up to $2 a pound, that’s a significant increase in carcass value to the packer.

One of the unique features of the gene, said Meyer, is that lambs who inherit it from the ewe do not show heavier muscle traits. The gene is there but you can’t tell by looking at the animal. If a ram inherits the gene from its mother, and passes it on, the lamb to receive it, male or female, will show the trait and pack on extra muscle. This is a phenomenon not found in any other mammals, said Meyer.

Even if the gene study does not prove fruitful for the lamb industry, it could shed light on the complexities of muscle development in all animals, including humans, said Meyer. “Our muscles function the same as animals,” he said. “It (the gene) has tremendous potential that we have not seen before. It’s been handed to us on a platter and we’d be absolutely foolish not to pursue it.”